• No results found

Latrines en septictanks : een literatuurbundel

N/A
N/A
Protected

Academic year: 2021

Share "Latrines en septictanks : een literatuurbundel"

Copied!
65
0
0

Bezig met laden.... (Bekijk nu de volledige tekst)

Hele tekst

(1)

Latrines en septictanks : een literatuurbundel

Citation for published version (APA):

Technische Hogeschool Eindhoven (THE). Bureau Ontwikkelingssamenwerking. Subcommissie Microprojecten (1973). Latrines en septictanks : een literatuurbundel. (Technische Hogeschool Eindhoven. Bureau

Ontwikkelingssamenwerking, Subcommissie Microprojecten : werkmap; Vol. 3). Technische Hogeschool Eindhoven.

Document status and date: Gepubliceerd: 01/01/1973 Document Version:

Uitgevers PDF, ook bekend als Version of Record Please check the document version of this publication:

• A submitted manuscript is the version of the article upon submission and before peer-review. There can be important differences between the submitted version and the official published version of record. People interested in the research are advised to contact the author for the final version of the publication, or visit the DOI to the publisher's website.

• The final author version and the galley proof are versions of the publication after peer review.

• The final published version features the final layout of the paper including the volume, issue and page numbers.

Link to publication

General rights

Copyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights. • Users may download and print one copy of any publication from the public portal for the purpose of private study or research. • You may not further distribute the material or use it for any profit-making activity or commercial gain

• You may freely distribute the URL identifying the publication in the public portal.

If the publication is distributed under the terms of Article 25fa of the Dutch Copyright Act, indicated by the “Taverne” license above, please follow below link for the End User Agreement:

www.tue.nl/taverne Take down policy

If you believe that this document breaches copyright please contact us at: openaccess@tue.nl

providing details and we will investigate your claim.

(2)

WERKMAPPEN

van de Werkgroep Microprojecten der Technische Hogeschool Eindhoven

Werkmap no. 3

Latrines en Septic tanks

een literatuurbundel

;

17,5f'?·

~)1" ~ !

l----»---..

4~,.'-.-_~._"""

I T. H. E I ~ iJ ~< !1 'y ~ N· : i 1o.-_ _ _ "P"' _ _ .... _ _ _ ~I_.I'«. ___ 1 Uitgave oktober 1973 Technische Hogeschool, Buro Ontwikkelingssamenwerking Postbus 513 Eindhoven / Holland tel. (040) 47.22.46 of 47.26.45

(3)

- 2

-Voorwoord.

In de uitzending van 16 juli 1973 heeft Radio Nederland Wereld-omroep aandacht besteed aan latrines en septic tanks • Verschillende

luisteraars hebben hierop gereageerd en om nadere inlichtingen ge-vraagd • Deze verzoeken zijn ter behandeling doorgegeven aan de T.H.

in Eindhoven. Om binnen redelijk korte tijd te kunnen antwoorden is deze literatuurbundel samengesteld. Wij denken dat hierin bijna aIle vragen van luisteraars beantwoord worden.

Uiteraard is iedereen voor nader advies van harte welkom. Schrijft U dan naar het adres op de voorpagina.

Tot slot twee verzoeken:

- wilt U ons de ontvangst van deze bundel bevestigen (er raakt veel post zoek) en schrijft U er even bij of U zo tevreden bent 7 - als U ideeen heeft, wilt U ons die doorgeven, dan kunnen wij

anderen er weer mee helpen.

Veel succes met Uw werk.

(4)

Inhoud

1. "Zelfspoelwaterverzorgende WC" uit het tijdschrift "de kleine aarde" van juni 1973. nit is de tekst van de uitzending van W.O. maandag

16 juli 1973. biz. 4

2. "Sanitary Latrines", de biz. 147 tIm 175 uit het Village Technology, Handbook, uitgave Volunteers for International Technical Assistance VITA,

College Campus blz. 5 33

Schenectady rew York 12308 U. S .A.

3. "Latrines, Aqua- Privy, Septic Tank", blz. 27 tIm 34, uit de

kalm-berichten van februari 1972. blz. 34 •••. 39

4. Vier bladzijden advies, gemerkt M.P. 68.05, over dit probleem eerder

door ons uitgebracht. blz. 40 •••• 43

5. Biz. 88 tIm 91 tiit "Grondbeginselen Bouwkunde voor de Tropen"

van H.Heynes. blz. 44 •••• 47

6. "kringioopsanitair", uit het tijdschrift "de kleine aarde" van december 1972.

7. Informatie over "Clivus", latrine plusseptictank. (dit is de beste van de antwoorden van punt 6)

8. Syllabus "Waste and refuse" van dr.V. van.Amelsvoort

blz. 48

blz. 49 blz. 59

N.B. Bij de keus uit bovenstaande mogelijkheden moet U er om denken

dat voor een septic tank een ruime voorziening van stromend water nodig is.

Bo/JJ/RR/23-10-73.

58 64

(5)

-4-zelfspoelwaterverwrgende we

door p. boxman

PI).C-·

JtI"...

~~ Jpl»lfye.

, ~f~I,)~~

'Sf~"',Ae~! '

Een eenvoudig klein kamertje is op (spoelwormen) . Gek is dit echter rijk is het dat er bij het schoonmak.en

de tuin onmisbaar. Dit mag merk- niet, want het menselijke darmstel~ van het toilet geen scherpe chemicalien

waardiger wijze zander vergwming. sel is niet ingericht op het verteren . gebruikt worden.

Mits van hout. Vooral als het cen van vIces. Het genuttigde vlees heeft Hierbij wordt een tekening gevoegd

~uincomplex is en er geen andere mo- in het lichaatn van een mens teveel van een septnank die ik een tiental .

,elijkheid in de buurt aanwezig is, tijd nodig am weer via de anale uit- jaren geleden gemaakt heb. Dezetank

kan dit een opgestopt gevoel veroor- gang teverdwijnen. Raakt men nu met voldoet nog altijd uitstekend. Hi} was

zaken. deze hardnekkige diertjes besmet dan berekend op een groot gezin, wanneer

Ernstiger wordt het als men overal komt men er niet zo gemakkelijk weer men bern maar spaarzaam gebruikt

in de buurt menselijke uitwerpselen af en zijn de feacalH!n een gevaar voor kan men de mat en rustigevenredig

vindt. Het is uitermate onsmakelijk de omgeving. kleiner nemen. Het juiste proces in

en gevaarlijk, zeer zeker op een Een eenvoudig toilet is dus geen over- deze tank heb ik ap gang gebracht door

tuin waar voedsel verbouwd wardt. badige luxe., ,Om stank en besmetting er een stuk rottend vlees in te gooien.

Het gebeurt nogal eens dat menselij- te voorkomen dient men de verz~mel- Op dit stukje viees hadden vliegenhun'

ke uitwerpselen hesmet zijn met Oxy- plaats verwijderd t~ h<?uden van water- eitjes afgezet en de nooige bacterien wa-,

uren (aarsmaden) en Ascariden . pomp. toilet en schuur. Heel belang~' ren ook door hen achtergelaten. ' .

(6)

Sanitary Latrines

The proper disposal of human waste is one Qf the most pressing public health problems in many rural communities. The use of sanitary latrines or privies can be very effective in helping to control disease. To stop filthborn disease, it is also necessary to have sanitary water supply, sanitary food handling, sufficient medical service and adequate diet.

Human nightsoil (nightsoil is a

~~~

~/~J.o' ('~.

~i~Y:~~,

~'-'~I,,;--:-r:

j

N.y.

iA·S.)J

Water privies: where a water- ' tight tank I~ceives the night-soil through a drop pipe or chute. An overflow pipe takes the di-gested material to an underground seepage pit or drainage area. wet pit, which does.

2.

Finally a water-seal slab may be used to cover either of these types of priv-ies to provide a completely odorless privy.

Other types of simple latrines are not recommended for general use, because they usually fail to provide enough sanitary protection.

term used for human excrement in many parts of the world) is a carrier of many diseases. These diseases are spread by water, soil, insects or hands. The sanitary latrine breaks this cycle. Some sicknesses that can be controlled by widespread use of sanitary latrines are dysentery, cholera, typhoid and wonms. The human suffering and eco-nomic loss caused by these is stagger-ing. It has been said that half of

A good privy should fulfil the

fol10w-. ing conditions: .

the food raised by a man with intestin-al parasites is consumed by the very worms that make him sick.

However, a latrine program must reach most or all of the people. This means

a carefully planned, continuing 10ng-range program with participation by government agencies, foreign workers, community leaders and most of all by the individual families. Proper la-trine designs which fit the cultural pattern are economically possible and

I

successful latrine program. Selected can satisfy the sanitary needs of a \~lans and designs for sanitary latrines lare given in the entries which follow.

~efore starting a latr'ine program for

~

our village, it is recommended that ou contact government and agency ealth organizations. observe their rograms and obtain their cooperation.

\

I

I

The recommended kinds of privies are:

1. Pit privies: a Simple hole in the ground. covered with a properly built floor. hole and shelter. It has two forms, the dry pit which does not pene-trate the water table and the

147

It should not contaminate the sur-face soil.

There should be no contamination of ground water which can enter springs or wells.

· There should be no contamination of surface water.

· Nightsoil should not be accessible to flies or animals.

· There should be no handling of fresh nightsoil; if it is neces-sary, it should be handled as little as possible.

· There should be no odors or un-sightly conditions.

· The method used should be simple and inexpensive in construction and operation.

Source:

Excreta Disposal for Rural Areas and Small Communities, by Edmund G. Wagner and J. N. Lanoix, World Health

(7)

-6-PRIVY LOCATION

Outhouses or privies should be close to the home, but they should be lower than water sources and far enough away from these sources that they will not pollute the water.

The information given here covers most normal situations, but it ;s al-ways best to have a trained sanitary engineer review your installation or program.

A latrine site should be dry, well-drained and above flood level.

If the bottom of a privy pit is in dry soil and at least 3 meters (lOt)

above the highest ground water table, there is very little danger that it will contaminate water supplies. This

is because the pollution will move downward no more than 3 meters with only 1 meter (3.3') of side movement.

(See section on "Ground Water"). If the privy pit enters the water table or comes close to it when the water is at its highest levei, pollution will spread to the water and endanger health.

Figure 1 shows the movement of pol-lution through the soil. It;s partic-ularly important to understand this movement when choosing a site for a privy or well. Put the privy downhill from the water source, or as far to one side as possible. On flat or gently sloping land, water moves toward the well as though it were going down-hill. This is because when water is removed from a wells ~ater from the surrounding soil flows toward it. Thus pollution from a nearby privy would move toward the well. If the land is

flat or if the well is downhill from the privy, do not put the privy closer to the well than 15 ~ters (50'). In sandy soil, a distance of 7.5 meters (25') is sometimes enough because sand helps to stop bacterial pollution.

148

These rules do not apply in regions containing fissured rocks or limestone formation. Expert advice is necessary in these cases, because pollution can be carried great distances through solution channels to the drinking water supply_

It is important to keep the latrine close to the house so that it will be used, but not too close. Putting the privy downhill also encourages use. People are more apt to keep a privy clean if it is close to the house.

Remember that

an

pr; vi es have to be moved when filled. This should be made easy or there will be a tendency to let them become overfull. This always re-sults in very unsanitary conditions and extra work to put the system in proper working order.

Source:

Excreta Disposal for Rural Areas and Small communities,

by

E.

G.

Wagner and

J.

N.

Lanoix, World Health Organization, Geneva, 1958.

(8)

BACTERIAL AND CHEMICAL SOu. POLLUTION PATTERNS ANOMAX!MUM MIGRATIONS· z, ...

J2;2~

I I I I- ---

~--- GROUND WATER ,1AiI_...

l .. ~"'I*r

FIGVR£ I

CHeMICAL lOlL POLLUTION .. ATT£ftlII

"--

... ,,,.,-,...,...-,,~,

..

-

..

The source of conlamination in these studies Will human

excreta pl.ced in a hole which penetrated the ground-w.ter table. Samples !IositiHe for coliform organisms were picked

up quite soon b&tween 4 m and 6 m (13 ft and 19 ft) from the

source of contamInation. The are. of contamination widened

out to a width of appreximate!v 2 m (7 ft) at a point about 5 m

(16 tt) from the privy and tapered oft at about 11 m (36 tt).

Contamination did no: move .. upstream" or against the direction of flow of the ground water. After a few months the soil around the privy ,lecame clogged, and positive samples

could be picked up at only 2 m to 3 m (7 ft to 10 ft) from the pit.

In other words, the area 01 soil contamination had shrunk.

The chemical pollution pattern is similar in shape to that of

bacterial pollution but e~tends to much greater distances.

From the point of view of sanitation, the interest Is In the maximum migrations and the fact that the direction of migration is always that of the flow of ground water. in locating weUs, it must be remembered that the water within the circle of infl vence of the well flows towards the well. No part of the area of che-mical or bacterial contaminatlon may be within reach of the

circle of Influen:e of the well.

MOVEMENT OF POLLUTION IN UNDERGROUND WATER

(9)

PRIVY SHELTERS

Several designs of privy shelters which have been found satisfactory in many parts of the world are shown in Figure 2. Important points to con-sider when designing a shelter are listed below.

Tools and Materials

Corrugated sheet metal roofing: 1.2m x 1.2m (4' x 4') or larger

-8-Wooden posts: SCIll x 5cm (2" x 211) and

20m (66') long

Boards: 2cm (3/411) thick, 20cm (8") wide, 40m (132') long

Nails Handtools

Paint: 2 liters (2 quarts)

The shelter should be built to suit the abilities and desires of the local people, because sanitary precautions are less important for the shelter than for the pit and slab. For a properly built shelter:

1. Choose a standardized design for economy in building.

2. Build the shelter to last as long as the pit, 8 to 15 years.

3. Build the shelter to fit the floor slab. It should not be so large that people wi 11 be tempted to use any part of the floor when the area around the hole has been soiled by earlier users. The roof should be 2m (6 1/2') high at the entrance. 4. Openings at the top of the shelter's

walls, for airing the interior, should be :Ocm to 15cm (411 to 6")

wide.

5. Some natural light should be let in. but the structure should give enough

150

shade over an uncovered seat or hole that flies will not be attracted. 6. The latrine should be kept neat

and clean so that people will continue to use it. Paint or whitewash the shelter. Cut back nearby vegetation. The roof should have a large overhang to protect the walls and the mound from rain damage and to'keep the privy area from getting muddy.

Source:

Excreta Disposal for Rural Areas and Small Communities, by Edmund G. Wagner and J. N. Lanoix, World Health Organ-ization, Geneva, 1958.

(10)

-IGVRE 2

!"'F SUPERSTRUCTURE RECOMMENDED BY US PUBLIC HEALTH SERVICE

/

HOUSE OF CUT LUMBER' WITH CORRUGATED METAL OR ASBESTOS CEMENT ROOF

HOUSE OF BRICK wn H TILE ROOF

(11)

-\0-PIT PRIVY

The pit pri vy descri bed here is the simplest recommended latrine or privy. It consists of hand-dug hole, a proper-ly mounted slab and'a shelter. Of the many existing designs for privies, the sanitary pit privy is the most widely applicable.

Tools and Materials

Materials for building the shelter Handtools for digging the pit, making

concrete and building the shelter The Pit

The pit is round or square, about 1m (3.31

) in diameter or 1m (3.31)

on each side, and usually from 1m (3.31

) to 3m (101) deep. The pit

FIG . .s VA .. IOUS PMT"~",

.OF A SANITARY PRIVY

A _ Pit B - Bale e .. Floor o - Mound E - Houle, Including door F - Ventilation G - Roof

Estlmated volume and depth*

I

for hole with 1 square meter area , Personal Cleansing Material

Solid (for example,

W a t e r grass or paper)

Years Volume in Volume in

Pit of cubic Depth in cubic Depth in

Type Service meters meters meters meters

4 0.7 0.7 1.1 1.1 Wet-Pit 8 1.5 l.5 2.3 2.3 15 2.7 2.7 4.2 4.2 4 1.1 l.1 1.7 1.7 Dry-Pit 8 2.3 2.3 3.4 3.4 15 4.2 4.2 -

-Figure 4. Privy capacities for a family of five. A wet-pit privy is one,which penetrates the water table. A dry-pit privy does not.

*Add 50cm to the depth given in the tab1e, because the pit should be closed and filled with earth when the waste comes to within this distance from the surface.

(12)

may have to be lined with brick, wood, bamboo or some other material to keep it from caving in, even in hard soil. The top 50cm (19 1/211) of the hole should be lined with mortar to make a solid base for the slab and the shelter.

The table in Figure 4 will help you to estimate the depth of hole to make. The Base

The base (see Figures 3, 5 and 6) serves as a solid, waterproof support for the floor. It also helps to pre-vent hookworm larvae from entering. If properly made of a hard, strong material, it helps to keep burrowing

rodents and surface water out of the pit. The pit lining will in most cases serve as a base although it may need to be strengthened at the ground surface.

FI6UI<£ 6

The Slab

A concrete water-seal slab is best. It is inexpensive but it means added

labor and construction. A concrete

open-hole slab is the next best, while a wooden floor is adequate. A built-up floor of wood and compacted soil is sometimes used but itis difficult to keep clean; as it gets soiled, it is likely to spread hookworm.

The concrete should not be weaker than 1 part cement to 6 parts of aggregate with a minimum of water.

It should be reinforced with strips of bamboo about 2.5cm (1") wide whose weaker fibers have been stripped away. Soak the bamboo in water overnight be-fore use.

Slabs (see Figure 7) are cast upside down in one operation. The footrests are shaped by removing part of the wooden form so as to make two separate

indentations in the wood. Sheet metal is placed around the form so that the metal extends above the wood to the thickness of the slab. Side walls of

(13)

-12-100 I ~I .... '.11 .ectlon a-a

Mea ... ...,mmu mown a'" In ""nUmel...,..

Mealurements shown .'" In centlmetret.

/II< - Centre open hole 2.5 em (1 In.) back of centre if IIIab Is 80 em (31 In.lln diameter; eentre open hole 8.0 em (3 In.) back of centre if slab is 90 cm (35 in.) In diameter

B Between back centre foot·resta C Reinforcement

Notes on construel/on o( slab

Concrete for alab. shOUld be not weaker thlln 1 part cement to II pllrt. aggregate, wllh /I mini. mum 01 water.

Slab Is reinforced with IItrips of bamboo of timber quality. Reinforcing ,trips are about 2.8 em (1 In.) wide, have had Inner, weaker flbres stripped away, and have bMn loa ked In water overnight before Ule,

Siabs are cast upsld" down In one operation, Sase of form la of wood with Indentationa for foot-rests. Sase of form is encircled by sheet metal strip which makes outer wall of form, Side walls of hole form and foot-resta are made with slight slope 110 as to come out easilY, Form for open hole's removed when concrete has taken initial set. Slabs afe removed from form In about 40 hours and stored under water, preferably for 10 days Or more. Since Ihese slabs are round. they may be roUed some dislance when conveyance is difficult,

(14)

the hole and footrests are made with a slight slope so as to come out easily. The form for the open hole is removed when the concrete first sets. Slabs are removed from the forms in about 40 hours and should be stored under water for 10 days or more.

Round slabs can be rolled some dis-tance when carrying ;s difficult. The Mound

The mound (see Figure 3) protects the pi t and base from surface I"un-off whi ch

otherwise might enter and destroy the pit. It should be built up to the level of the floor and be very well tamped.

It should extend 50cm (2011

) beyond the

155

base on all sides. The mound may be built much higher than the ground in areas where protection is needed against floods and high tides. It will normally be built with earth removed from the pit or the surround; rig area. A stone facing will help to keep it from being washed away by heavy rains. In front of the entrance door, a masonry or brick step can be built to help keep the floor clean.

Source:

Excreta Disposal for Rural Areas and Small Communit':es, by Edmund G. Wagner and J.N. Lanoix, World Hea1th Organi-zation, Geneva, 1958.

(15)

WATER PRIVY

A water ( or aqua) privy uses a watertight tank in which human ex-creta and urine partially decompose. A sewer pipe connects the tank's overflow pipe to an underground drain area or seepage pit.

This is a sanitary and permanent installation when it is properly

built~ used dai1y and maintained

properly. It can be placed near a building. The first cost of a water privy is highs but it is not expen-sive in the long run because it will be used for many years. It needs some water and cannot be used in freezing climates. The water privy may not be. successful in rural areas with no organized sanitation and

health education services. The Process

The digesting or decomposing tank

-14-156

is usually made of watertight con-crete (see Figures 8, 9 and 10). A drop-pipe, 10cm (4") in diameter, attached to the squattin9 plate or seat hangs down 10cm (4") below the surface of the liquid in the tank. This forms a water seal which keeps bad odors from rising into the privy shelter.

The decomposition process forms a sludge in the tank. The amount of sludge is only one-fourth the volume of the total waste deposited in the

pit, because some of the solid matter breaks down into very small pieces, liquid and gas. The liquid and the pieces of waste matter run out the overflow pipe to the drain field. The material which flows out is called effluent. The gas escapes through a vent pipe.

FIGI/RE8

(16)

T

30

1--15

---j

The Tank

The tank must be watertight. If the tank leaks, the liquid level will fall below the drop pipe, odors will form, flies and mosquitos will breed,

and the soil and ground water will be polluted. Tanks made from bricks or stone and mortar must be faced with a coat of rich cement plaster to make sure they are watertight.

The tank can be made of plain concrete sewer pipes 90 or 120cm

(36" to 4711

) in diameter and sealed

at the bottom with concrete (see Figure 10).

Family-sized units should not be less than 1 cubic meter (35 cubic feet), which will usually allow 6 years or more between cleanings. Thus the family water privy need not be too deep, which is an ad-vantage in rocky ground where the water table is high.

Drop-pipe

The 10cm drop-pipe with its end lOcm below the surface, prevents water from splashing and improves

1=/fi,VIIE 9

ALL DIMIiiN$IQAlS / N eM

flushing. Nightsoil may siick in the pipe from time to time and must be flushed or poked down to stop odors and to keep flies from breed-ing. The pipe may be up to 20cm (8") in diameter and reach 20cm be-low the surface of the water in the pit, which will prevent sticking, but this size will release more odors and cause splashing, and the pipe may crust over.

Disposal of Effluent

Disposal of effluent from a family unit is usually done in seepage pits or by below ground irrigation. The amount of effluent is equal to the amount of nightsoil and water put into the digesting pit. This aver-ages 4.5 liters a person each day, but the drainage system should be designed to handle 9 liters a person each day. When a water tap is inside the privy, the effluent disposal system must be much larger. Too much water causes poor digestion of sludge.

The area of below ground irrigation ditches or seepage pits needed for a family of five will be from 1.4 square meters (10.7 square feet) in

(17)

-

"I 00 I ::l iZ '::J.

~

SOIL ---tF"--

6

-, l'iQiXi . SI:.EPA6.E' I PlT

7

OPEN JOliNTS I ROCK. I=\LL .J -' u: X IJ ~

90eM OR, 120 eM OIA.

SGWE/Z, PIPE J 90 CM J.ON& OR MORE) S.eALGD WlrJ./ CONCRETE AT LOWER ENJ>. FIGURE 10 91

«l1:i

b4 .

.. -, . -.. '

-

... / / / / / ..,-// Nol ;11 Scali!' Ollnel15iol1s in em.

(18)

very 1 i ght so"11 to 5 square meters (53 square feet) in soils that are hard to penetrate.

These methods are not practical in regions where the water table. rises to within 1m (31

) of the ground

surface, or in clay soils or swampy land. Here some type of sand filter may help, but this requires help and approval from local health experts and continued maintenance.

Operation

The first step in putting a new water privy into operation ;s to fill the tank with water up to the overflow pipe. Digested sludge from another privy can be added to the tank; this will seed the water and start the de-composition process. If the tank ;s not seeded, it will take about 2 months for the process to get going effici-ently. Once this level of operation ;s reached, the privy will keep the process going, provided it is used daily. Cleaning and flushing the slab and bowl daily with 25 to 40 liters (6 to 10 U.S. gallons) will give the tank the small amount of water it needs to keep the process going.

Removing Sludge

The sludge which forms in the tank must be bailed out before the tank is half-full, about 6 to 8 years

after the privy ;s put into operation. A manhole, often located outside the shelter, ;s made for this job.

Not; ce in Fi gure 8 that the tank floor slopes toward the manhole for easier cleaning. Both the vent and the dra; n are eas i ly reached. The drain has a T-shaped section which helps to keep hard surface scum from entering and plugging the drain and whose shape. makes it easy to clean.

The overflow pipe in Figure 10 ;s an elbow.

Bury the sludge in shallow trenches about 40cm (16") det:p.

Source:

Excreta Disposal for Rural Areas and Small Communities. by Edmund G. Wagner and J.N. Lano;x, World Health Organi-zation, Geneva, 1958.

(19)

-18-PHILIPPINE WATER-SEAL LATRINE

A water-seal bowl improves a latrine by keeping flies out of the pit and preventing odors from escaping. The mold described here (see Figure 11)

has been made and used successfully in sanitary latrine programs in the Philippines. The advantage of this mold over a concrete mold is that its manufacture requires no drying time. Tools and Materia'i.s

Wood: 19mm (3/411) thick, 31cm

(12 1/411) wide and lS2.Scm (S') long

Galvanized iron: O.7Smm x 32cm x 40.Scm (1/32 11 x 12 1/2" x 16")

La rge na i 1 s : 18

Cement and clean sand

Galvanized wire: Smm (3/16") in diameter and 30.Scm (1') long, for interior mold handle

Bamboo pole or iror. rod: 30.Scm

(1') long, to position interior mold

Making the Mold

If the materials for the mold are cut according to Figures 12 and 13, the bowl is easy to make.

1. Nail the metal sheet around the curved back of the mold (see Figure 11).

2. Attach the two front pieces with large nails through the loose-fitting holes. These holes make it easy to remove the front pieces. The extension at the bottom of piece No. 1 is important in mak-ing sure that the bowl will seal well below the water level. Making the Bowl

Since the mold nas no bottom, find a flat place to work where the mold

can b~ propped against a wall. Fill

the mold wIth n mlxturu of two part ..

fi ne sifted sand to one part cement.

160

FIGVIl£ /I

Use only enough water to make the mixture workable. Pack it in so that there are no airpockets. Let it set for 1S to 20 minutes until the mix-ture is stiff. Next, with a ruler, measure a 38nm (l 1/211) wall around the top and outlet and di~ out the inside with a tablespoon (see Figure 14) •

Keep a straw handy to gage the thickness of the walls of the bowl while digging, because it is difficult

'-'-""r"

_I..\) ~lPE - "two ~~Ull!1> I L/(>-~~ .,"\"

7

'\'0 'l'J.1II'1I.'!o :. ~ .-.. ; . : ~ J>l"l~t.o"",.. ,.~ - 1 -'.~M"'~ ~t~,'Z

(20)

~. -·,tfC/tlf-- --

+--

--14CM--1

, • t

-\ -

-,

l

I

(.\.c,,,.

~t

S"'" \ NO. I I r:ot .... fI).\"

\JO

_J_

: r':+.'fr-1i

~

i !--6...,-...L6.1--i I-T

I

eM

I

~"" I SCM - _1 - - '---+---1

f--g;!

:!

..j FIGUIiE 1.5 [-·-10& .... -+----IDCH---I ( - - ' '-'-i .I'.8G.M I -~-I loe/lll

I

·

--r-3.8'/111 - --- '---'--- ~_~ _ _ ...J--L._ I j-

-"'~-T,-.!,.~--

CM eM

..

I

to judge otherwise.

Dig out the large interior first, then the outlet. 'fhe finished in-terior of a bowl is shown in Figure 15.

P'IGVRE 15

-Be sure you can insert three fingers vertically, Scm (211), through the hole leading to t~e outlet. Be care-ful to release front piece No. 1 by inserting the spoon around the edges (see ~igure 16).

After the interior has been dug out, the walls will have slumped down

about an inch. Use the cement taken from the interior to build the walls back up; then smooth all exposed surfaces with the back of the spoon as in Figure 17. To be completely

~~~~~~~====:::::7' sani tary, the bow1 must be as smooth

~-,

---_._--PIGl/RE 14

as possible so that germs cannot accumulate in crevices.

For a finishing coat, one of two methods may be used: (l) il11llediately after smoothing, sprinkle dry cement over the sti 11 wet surfaces and smooth again with the spoon; or (2) let the

bowl set for half an hour and apply a mixture of pure cement and water --a coconut husk brush is good enough. Either method gives good results. See Figure 17.

(21)

/

..

o

For a luxury product, use white or red cement for the finishing coat; several coats are necessary.

The finished bowl should be left in the mold to dry 48 hours. It can be removed after 24 hours only if extreme care ;s taken. Pullout the front nails and remove pieces No.1 and No.2; pull the sides and back

away from the bowl.

-20-162

FIGU/lEI6

Making an Interior Mold

Because digging by hand is tedious and because it must be done very carefully to make the walls con-sistently thick, it ;s better and faster to use an interior mold.

After the first bowl has hardened thoroughly, fill the outlet with dry sand so that the cement cannot

(22)

flow into it. This would make it impossible to remove the interior mold when it hardens (see Figure 15).

Li ne the large inter; or with paper and fill it with cement -- a 4 to 1 sand-cement ratio is good enough.

Insert a heavy wire loop in the top so that the interior mold can be positioned on the exterior mold with an iron bar or bamboo pole.

F/G;UREI8

When an interior mold is used. it is only necessary to dig out the out-let. It is a good idea to have several

FI6URIi"' /9

interior molds, but not necessary to have one for each exterior mold. The interior mold should be removed after 15 to 20 minutes so that the bowl can be smoothed and finished. Then it can be used to make the next bowl.

Using the Interior Mold

To use the interior mold, fill the wooden mold about 12.Scm (511

) from

the bottom and i nset't the i nteri or mold in the correct position. See Figure 16. Push the cement around the mold with a stick and pack it well to get rid of air spaces. After the molds are removed, the finished bowl should be left to dry until it is rock hard -- a week is usually safe -- before delivery.

A sand-cement ratio of 2 1/2 to 1 has been used successfully with the bowls. A ratio wider than this may be too much of a Sacrifice of strength for profit; customers may be dissatis-fied and sales may drop. There are many ways to strengthen cement; ex-periments may bring a cheaper and better profit. One possibility is to add short coconut husk or abaca fibers.

(23)

-22-'if;·· ...

f:'IGlII?E 20

Installing the Toilet

For use in private homes, dig a pit about 1.5m (51) deep and 1m (3 1) square. The deeper the pit and the smaller the width the better, since a small slab is cheaper (see IIPit Privyll Section). It can even be dug under the house -- especially in cities -- because the toilet gives off very little odor, unless of course this ~os;tion endangers the household water supply. The pit may be lined or unlined, depending

164

upon the soil. Hard clay soil need not be lined. But, if the house is near the sea or on sandy soil, the pit should be lined with, for ex-ample, bamboo poles or hollow blocks as shown in Figure 20.

Place boards around the outside of the pit 15cm (6") from the edge of the pit to form the perimeter of the slab (see Figure 21). Place large pieces of bamboo split in half across the pit as a base for the slab. Place the bowl between two of the

(24)

bamboo pieces with a piece of wood under the front and back; nail these to the bamboo. After the bowl is positioned in this way, pour water into it to be sure it will seal off the outlet. The top of the bowl should be 7.5cm (3") above the bam-boo base.

Now put bamboo slats across the pit at right angles to the large pieces of bamboo, completely covering the pit. Cover this with several thick-nesses of newspaper. Pour cement around the bowl until the slab is

1

"about §S;I!Ll4.':) th i ck. A mi xture of

'o~~· two kerosene cans of gravel, two of

sand and one of cement is good. The slab can be reinforced by placing bamboo slats between two layers of cement. Make sure that the outer edge of the slab is higher than the bowl and slants toward the center, so that the toilet can be easily cleaned. Apply a finishing coat of pure cement to the slab. Many people prefer to add foot rests and urine guard--there is room for imagination.

It is extremely important to have an ample water supply at hand. About 1 liter (1 quart) of water is needed to flush the toilet, and people will be discouraged from using the latrine properly if they have to go some distance for water. It is a good idea to have an oil drum or a small cement tank nearby to supply water for the 1 atri ne.

Do not use the latrine for at least 3 days -- a week is best -- after it is installed.

A pit with the suggested dimensions should last a family of eight about five years. One person uses about 28 liters (1 cubic foot) a year. Source:

"Campaigning for Water-Sealed Toilets,1I by Gordon Zaloom, Peace Corps Volunteer.

(25)

-24-THAILAND WATER-SEAL PRIVY SLAB

The Thailand Water-Seal Privy Slab, made from concrete, is useful for large-scale privy programs. The slab, which includes a bowl and trap, is used to cover an ordinary ~it privy. It comes from a long-established privy program in Thailand.

Master molds for th~ bowl and trap are used to make secondary molds from which the bowl and trap are actually made. The master molds can be made

from the plans in the entry which follows. The master molds can some-times be purchased from local health officers. In Thailand, they can be purchased from the Village Health and Sanitation Project, Ministry of Pub 1; c Hea lth, Bangkok.

The finished slab is quite strong because its three parts are cast at the same time (see Figure 10). The method described here can be applied to other water-seal slab designs. Tools and Materials

Master molds

Materials for making concrete Wood for platform fonns

Reinforcing rod and wire Clay

Crankcase 0; 1

Beeswax and kerosene (optional) Steel bars: 19mm x 19mm x 7.Scm

(3/4" x 3/4" x 5")

The basic method for making these water-seal slabs is to cast the slab, bowl, and water-seal trap using three forms:

1. A wooden form for shaping the slab (see Figure 6).

2. A concrete bowl core for shaping the inside of the bowl (see Figure

3) •

166

J:"/GU.e£ ,

~rTCN OF .!='//Y/$NE,o PN/VY.

3. A concrete core for shaping the inside of the water-seal trap (see Figure 9).

The water-seal trap is curved back under the bowl as shown in Figure 2a.

A.

8ACKWAA!D

FJ.U$J.//Ntf.

TRAP

(26)

This makes flushing more difficult, but prevents erosion of the back of 'the pit on loose soil. The same gen-,eral method could be used to make a ,forward flushing trap (see Figure 2b).

The forms used when making a slab

I must stay in place until the concrete

, is strong enough, usually 24 hours. For this reason. many sets of forms are necessary if a reasonable number of slabs are to be cast every day. Here is where the three master molds are needed; one of them to cast the bowl core, and the other two to cast the trap core (see Figures 14 and 18). Casting the Bowl Core

1. Oil the inside of the master bowl mold and insert a 19mm x 19rrrn x 7.Scm

(3/4" x 3/4" x 5") steel bar into the bottom.

2. Add a fairly loose mixture of cement and water, called neat cement, to a depth of about (611

) . Then fill

to brim with a 1:1 cement-sand mixture. The 1:1 should be firm, not runny, and should be laid into the loose neat cement without stirring to insure a smooth finish on the bowl core. 3. After the bowl core has become firm enough, scoop a depression into the surface to install two steel hooks made from the reinforcing rod. They should be about 22.5cm (911

) apart,

and should not protrude above the

surface of the concrete. See Figure 3. DEPRESS/ON Uti' 80W~ caRl

~~~~==~==~~~;~~~L6

FI.VNE.J sow,,- CORE HANJ>L£6

4. Let the concrete set at least 24 hours before removing the bowl core from the master mold ... The bowl core can be used to make another master mold and the master mold can be used to make more cores.

Casting the Trap Core

1. Add about 2. Scm (11) of 1: 1 cement-sand mix to the oiled trap master mold and put in some wire for

reinforcing. Then fill it with 1:1

almost to the brim. See Figure 4.

FIGVRE.p .Ii'£INFO/icING rH£ 'TRAP COIZE

2. Put the oiled insert mold into place and scrape off excess. See Figure 5.

FIG(lR£.s Pt.ACING TUE'

IN$G/i!r MOJ..t)

'.'

" '.'

(27)

-26-3. After 45 minutes, remove the in-sert and put a square sheet metal pipe 19111T1 (3/4") high into the cubical in-dentation left by the insert. The pipe is made by wrapping sheet metal around a 19111T1 x 19111T1 (3/411 x 3/4") steel bar. let the concrete dry in the mold for 24 hours.

4. Remove the finished trap core by tapping the master mold gently with a wooden block.

Making the Wooden Slab Form

1. Make a wooden platform 90cm x 90cm (35 1/211 x 35 1/211) out of ·2.5cm (1")

thick planks.

2. Cut out of the platform a hole lOcm x 33cm (411

x 13") for the hooks of the bowl core to extend into. The back of the hole should be 28cm (11")

from the back of the platform. To determine the location of this hole, draw the outline of the bottom of the bowl on the platform, with the back of the bowl outline 23cm (9") from the back of the platform. (See Figure 6.) The back of the hole

shou 1 d be 28cm (11") from the back

of the platform.

So eM.

~--- 8oeM- -+---+~

3. Using 38mm x 38!l1T1 (1 1/2" x 1 1/2") wood, make a frame with inside dimensior of oocm x 80em (31 1/2" x 31 1/2"). (SeE Figure 7.)

4. Gouge out the footrests with a wood chisel. The inside of the foot-rests should be about 12.SIl1T1 (1/2") from the outline of the bowl.

/

~~~---~~~~=7~~HH.

(28)

lsting the Slab

With these three forms finished, )u are ready to cast the first water-eal slab.

• Use a paintbrush to coat the )wl core and the trap core with a ayer of wax about 3mn (1/811

) th i ck.

repare the wax by dissolving lkg 2.2 pounds) of melted beeswax in .5 liter (1 pint) of kerosene. he wax coating will last 5 to 6 astings adding U.S. $0.01 to the. ost of each slab. Wax makes re-oving the cores much easier, but

t is not absolutely necessary. et i t dry before

oiling-_ Place the bowl core on the wooden lab form and fill all cracks with lay. See Figure 8.

Ir.,U/IC:1;; 8. SEAliNG- CRACI<S WITJI ClAY.

Oil the bowl~ platform and frame. Apply a 611111 (1/411) thick coat of ty cement and water mixture to the 1 core and platform. (Many Thai ple prefer to spend U.S. $0.25 re for an attractive polished slab.

do this, instead of using a mix-of cement and water, use a mix

169

of 5 cement: 5 color: 1 granite chips. After the forms are removed, polish with a carborundum stone and plenty of water.)

5. Cover the bowl core with a 1:2 ce-ment-sand mixture to a total thick-ness of 12.Smm {l/2"}. Make a

smooth lip on the cement 10mm (3/8") from the top of the bowl core as in Figure 9. This lip is your water seal. Use fairly dry cement and let it set for 15 minutes before cutting thi s 1 i p.

6. Place the trap core on the bowl core and seal the crack with clay. Also add a little clay on each side of the form (near the thumb in Fig-ure 9) to prevent cement from get-ting to the front lip.

FIG{/R£ 9. MOVNT/NG TNE 7"QAP CORE.

7. Cover with 1:2 cement-sand mixture to a thickness of 12.Smm

(1/2" ). Do not exceed the 12. 5rml

(l/2") thickness below the trap core or you will not be able to re-move this core.

8. Fill the slab form with a mix. ture of 1 cement: 2 sand: 3 clean gravel or crushed rock almost to the top. In preparing the concrete, first mix cement and sand, then add gravel and water. Use water

(29)

-28-ture, the weaker the concrete will be.

9. Press in 4 pieces of 6nm (1/411) steel reinforcing rod. See Figure 10.

FIGURE /0. PJ.ACING REIN,l:ORCING ROO.

10. Fill to top of frame and smooth. Allow at least 24 hours for setting.

11. Remove the frame by tapping lightly with hammer.

12. Turn the slab form over on a wooden stand and use simple levers to remove th~ bowl core. You must remove the bow'l core before the trap core. See Figure 11.

F/Gl/RE II. REMOVING rR.E'

BOWL. COilE".

170

13. Tap the trap core gently and slip it out. Add a little water and check to see if your seal is'lOmm

(3/8") .

14. Keep the slab damp and covered for a minimum of 3 days and preferably a week to gain strength.

Source:

Thailand's Water-Seal Privy Program, by Barry Karlin,

MPH,

Sanitation Advisor, USOM/Korat, Thailand.

(30)

This entry describes how to make the three master molds from which cores can be cast. The cores in turn are used for casting Thailand Water-Seal Privy Slabs.

Tools and Materials Cardboard

Materials for making concrete Steel rod, 19mm (3/411) square Sheet metal (tin-can metal is

sat; sfactory) Reinforcing wire Clay

Oil (used crankcase oil is satis-factory)

Paint brush

Making the Master Molds

It may be necessary to make master molds rather than to purchase them. Study the entry IITha i'1 and Water-Seal Privy Slab" before starting to make these master molds:

1. The Master Bowl Mold,

2. The Master Trap Mold, and

3. The Trap Mold Insert. Making the Master Bowl Mold

1. Cut out profiles of the bowl out-line from Figure 13, which is ~~aH

size.

2. Shape a mound of clay using the carboard profiles as a guide.

3. Form a little square pipe, 19mm (3/4") 1 on~, of sheet metal on the 19tm1 (3/411

) square steel rod. Make

several of these as they will be used later when casting the cores. Fill the square pipe with clay and press it into the top of the clay mound a little bit. This will be used later to "key" the cores to-gether. See Figure 12.

.'_ .4. Use a paint brush to paint the

171

FIGV./ZE 12. ClAY MOt/NO

clay mound with oil; old crankcase oil is fioe.

5. Cover the clay mound with a stiff mixture of cement and water to a thickness of 12.5mm (1/2"). If the clay mound was properly prepared, the inside finish of the bowl mold will need no further smoothing.

6. After this cement has set 30

minutes, build up the thickness to 38mm (1 1/2") with 1:1 cement-sand mix. let this set 24 hours and carefully lift the finished master bowl mold from the clay mound. The finished bowl mold is shown in Fig-ure 14.

Making the Master Trap Mold

1. Make cardboard profiles of the trap from Figure 17, which is ..;t:u..14Y-.alf

size. Shape the outside of the trap from clay, and let it harden over-night.

2. Shape the under side by hand with a trowel using Figure 15 and the in-sert profile from Figure 17 as guides. Mark the location for a 19mm (3/4") square metal pipe by holding the clay trap over the clay mound used to shape the bowl mold, and letting the square sheet metal cube mark the trap. 3. Insert the sheet metal pipe into the clay trap and scoop out the clay

(31)

-30-..---

- - - ,

\ 1"--\ I

\~--~----~~~---~~----~~--~I

\

\

I

\

I I I

\ I

\ I

\1

,

,\

\

I \

I

\

I

\

I ~ \

\

\

\ f

\

I

\

I

\ Sl.'£)£ \ \ \ \ \ \ \

\

\

\

\

\ I

Y .I \ /

/

/

/ .

\

I

\

/ I I / /

I

I

I

\

I

\

L.... ___

+- __________ / __

.J

l ___________

...1

FIGURE 13· PJ?0J:rILE5 FO;e MAkING MAsrGIi! MOLt:> ,j:"01Z

(32)

from inside. See Figure 15. Check the clay trap on the bowl mound again to be sure it lines up properly.

4. Oil the clay trap.

5. Put a heel-shaped piece of clay under the clay trap and trim the sides. This will prevent the cement from running under the mold. See Figure 16.

6. Cover with cement and water to

1911111 (3/411

) , add steel rei nforei ng

wire, and cover with 19nm (3/4") more of 1:1 cement-sand mixture.

7. Flatten the top and insert wire handles. Let it set at least 24

hours. This completes the master trap mold.

FIGVI2£ IS. ClAY rRAP

173

F/6l/Ii'E /6.

PREPAR/N(f;

CLAY r.leAP

FOR CAST/Nt; Ma'l)

Making the Trap Mold In3ert

1. Turn the master trap mold over carefully, and remova the heel-shaped clay plug.

2. Oil all inner surfaces and fill to the brim with 1:1 cement-sand mix. 3. Insert a small w~re handle and let the concrete set for at least

24 hours before separating the finished molds.

(33)

:--..

-.

, ,

"\

\

)

I

.

/

./ '" / / I I

.

I , ( • I • I • \ •

,

'-, \ \ (

.

I I \

~~

\ \

---10·

. ,---- ____ J

-

---

... ,.

...

I '.

I_J-..J

L.--·'--

I I I I / I I

"

,

\. \ \ \ \ , \ \

,

\ \ \ \ \

,

\ __ L _ _ _

-

-

-

-

-

-

-

-

-

- -

-

- -

- -

~-

-I I

FIGVR£ /~. PROFIL.ES FOil MAKING MA5TE/i! MOLOS

FOR TRAP (FVJ..i.. SIZE)

I

.

-

,

/,'

..

. /

.

J I I ~ I

!- - . - -

~

'I. ____

i

(34)

F/(f;V,fJ,E IS. "TRAP MO/..D

AND IN.sE'gr

Figure 18 shows the completed master trap mold and insert.

175

Source:

Thailand's Water-Seal Privy Program~

by Barry Karlin, MPH Sanitation Advi so r, USOM/ Ko\:"a t, Tha i 1 and.

(35)

-34-\< A,L M ...

L A T R I N__ S A QUA - P R I V Y ~ e: '\t\<...H-re:t\

"F Ell R.

7

"l.

S E P TIC - TAN K.

Als er op een bepaalde plaats geen riool is, is men aangewezen op een latrine. Vooral in warme streken kan deze latrine een bran van besmetting zijn, want vele ziekten worden verspreid vi'1 de ontlasting. Als een latrine zieh in de buurt van een Haterbron bevindt, kunnen de ziektekiemen getransporteerd wor-den door het grondwater of door urine die zieh hoven de grand een Heg baant. Men moet latrines altijd eF een afstand van ~instens 6 meter van de dichtstbij-zijnde bebouwing inaken, en i-Tel zo dat bij een mogelij-ke overstroming je urine van de huizen wegstroomt. Oak mag de latrine zieh niet langs een pad a:: i-leg be-vinden.

Ontlasting als bem~sting.

Men mag nooit onbeh~ndelde ontlasting gebruiken voor bemesting van groenten e.d.

Op die wijze zou ,nen de planten via opspattend water of opwaaiend stof besmetten met virussen, bakterie-en of eitjes van parasietbakterie-en.

Hen moet de uitwerpselen voor bemesting eerst behande-len: Als men toiletemmers leegt, moet men dit doen in een kuil met een maxima Ie diepte van 40 em omdatan-ders de "mest" niet verteert wegens zuurstofgebrek. De lengte van de kuil kan bijv. 3 meter en de breed-te 1 mebreed-ter zijn. Elke keer als men met een emmer ge-leegd heeft, moet men het oppervlak bedekken met enige em gronq om stank en besmetting door vliegen te ver-mijden.

De kuil moet mlnstens 500 m van het diehtstbijzijnde \<Tater ve:pwijderd zijn. Als de kuil vol is, moet hij bedekt worden met een dikkerelaag grand, waarop een vaste bedekking komt, am te voorkomen dat dieren de kui~. cm"H'ror:;tcil:"!: C:;..;.t c. :c,_[~en de bedekkende

grond wegspoelt. Op deze manier voorkomt men oak dat parasietenlarven omhoog kruipen en door voorbijgangers

"oD0.eloDenll worden. Na + 8 i-leken" is het alval

vel'-te~;d t~t humus. De inhoud van de kuil kan dan, na vermenging met viermaal het volume aan aal'de, als tuingrond gebruikt worden. Om de hygiene op te voe-ren verdient het aanbeveling de toiletemmer af te schaffen en een gezonder systeem te gebruiken.

(36)

AQ U A

I

I

·L

PRIVY fig. 1. valvlater of regenwater.

De Aqua-privy bestaat uit een tank, gevuld met wa-ter. Hierin mondt een pijp uit die van de vloer . van de la~ine naar beneden loopt tot onder het ''''3teroppervlak in de tank, di t om stank te vermij-den. Om de zelfde reden mag de diameter van de pijp niet groter zijn dan 10 - 11 em.

De faeces en de urine vallen door de pijp in de tank \:aar . deze anaeroob, d. w. z. zonder toevoer van lucht, verteren. Er blijft dan slib over dat nog maar een i<:\,art van het oorspronkelijke volume inneemt. Dit slib ;loOpt zich op op de bodem van de tank en moet van tijd tot tijd vel'wijderd Horden. Di t dient te

g~tcuren als de tank voor de helft ~vuld is met slib en men kan het doen met een emmer aan een

~teel. Om het.legen mogelijk te maken moet men in de to'lcnyantvan de tank een mangat van 50 em maken, afgedekt met een goedsluitend deksel.

De tank kan elke vorm hebben (rond, viarkant enz.)

Capaciteit: per persoon 115 liter. Als de tank dus een volume heeft van 1 m3 kunnen er gemiddeld 9 personen gebruik van maken.

D":epte: 2,30 meter.

t ' . 1 t 1

,wl?;,crr20og .e ,75 meter

We:r>kLJijze: Naak de tank. van geml t "elde stenen en bep:'eister deze met een dikke laag cement, of ge-bru~k gewapend beton van 20 em dikte.

De :ank moet absoluut water-dicht zijn •

. Bij lekkage

kanbe'sme'Fdng-van

het wate:t:' in de huurt optreden en bovendien zakthet vlater beneden de uitmonding van de valpijp, en daardoor zal stank. optreden.

In verband met dit gevaar voor het optreden van lek-kages moet de tank op grote afstand (500 m) van het dichtstbijzijnde water liggen.

Zuaht-Omdat er bij de vertering van h~t materiaal veel gassen gevormd worden, moet er een smalle luehtpijp op de tank gemaakt worden. De opening wordt tegen de vliegen afgeschermd met roestvrij gaas.

Het grootste nadeel van deze tank is dat hij gere-geld geleer.;d moet Iwrden. Hierbij moet men oppassen

~~~~~niet bedwelmd te raken door de uitstromende gassen

0" SSm en zeker niet in de put te vc.:'.len. De gassen zijn giftig.

Een eenvoudiger methode is de volgende:

TAliK l,,75m .-..!~-water gewapend beton i 1

I

i I t I !

f

..

I

(37)

-36-Deze bestaat eveneens ui teen tank gevuld met vIaLSI'. Nu is de I'uimte verdeeld door tussenscnotten h'aari!l beurteling oader en boven een opening gemaakt is. is om de weg die het water in de tank· aflegt zo larcg mQgelijk te maken. Een ander verschil met de Aqua privy is, dat het behandelde water direkt afgevoerd \-vordt en dat er nauweIijks slib over blijft. Hoewel men weI af en toe moet kijken ofer niet teveel slib gevormd is, vergt de septic tank in het algemeen

Hei-nig werk.

Aan het einde van de tank bevindt zich een afvoer-pijp die Ieidt naar een zakput of iets anders ( verder

in

Jit artikel)' In geen geval mag het 1,,,aLer direkt ui t de septic tank naar open water "orden ge-voerd. Het water is weI ontdaan van de meeste vastE

stoffen, maar het kan nog weI degelijk ziektekiemen bevatten.

Capani tei t: Bii pen gpmjddeld aantal gebruikers vaIl

20 rekent met 0,4 m3 per persoon, bij meer dan 20 gebruikers 0,3 m3 per persoon. Als er geen spoelwater, afval- of

regen-water in de tank gebracht wordt, kan men de helft van het volume rekenen.

rZoeistofdiepte: 1,20 - 1,70 meter

Ruimte boven de vZoeistof: 0,30 meter

Lengte: 2-3 maal de breedte.

Onderhoud: Ieder half jaar inspektie houden. Er mag niet meer dan 50 em slib in de tank aanwezig zijn. Slib verwijderen met emmer aan een steel.

J.'C:l'h·ljzc: Baak de tank van gemetselde stenen be-stl'eken n:et een dikke laag cement of gebruik gewapend [vt0n (20 em). De tank moet waterdi cht zijn en Yoor-::.i""n van een met gaas afgeschermde Iuchtpijp.

Bet is, door de '''erschillende tussen-schotten nodig meerdere mangaten te maken •. Deze moeten ook hier

sluitend zijn. Hat is absoluut nodig deze tank evenals de vorige, in het begin te vullen met water.

A~ders werkt het verteringsproces niet.

Bet aantal Tussenschotten is uiteraard afhankelijk v;m het aantal mensen voor wie de tank bedoeld is.

r.OJ als stelregel dat het eerste kompartiment 0,5 m3

maet . Als de put voor bijv. 8 - 10 mensen is b,:c.oeld, is een tussenschot weI voldoende ~

(38)

,

---1,20m tot 1,70m SEPTIC TANK fig. 2.

pOl"euse Won(~ van baksteen

(39)

-38-~/ctera{1'voer.

---~----Z::;31s boven al vermeld werd, is het beslist

noodza-Ccc;.:.ijk dat het water dat uit de tank kornt, nabehan-~e:d wordt. Er zijn verschillende method en om dit te doen.

Als men een ~oorlatende grondsoort heeft - dit kan mer: kontroleren door een kuiltje te gn:v€;n ~

dit te vullen met water en dan te kijken of dit na niet alte lange tijd wegzakt, vooral zandige gron-den zijn geschikt - raakt men het 'VIater kHijt doOr het i~ een zakput te voeren (zie fig. 1).

Deze m:akt U door een put te maken vanporeuze bak-steen, :lie omgeven wordt met een dikke laag grind of fijr: pm:-l.

Een ar.dere mogelijkheid is dat men

drainage-~yet~em ~anlegt van poreuze :rainagebuizen met een diameter van 8-10 em. Deze graaft men in op 40-50 em diepte en om1eeft deze met een bed van grind of fijn puin. Dit systeem zal vooral op het platteland waar men grond genoeg heeft, voldoen. Het best kan men vier "armen" op een afstand van 1,5 meter' van elkaar leggen (zie fig. 3).

De tot ale lengte zal afhangen van de af te voeren hoe-veelheid water, de doorlatendheid van de grond en de soort buis die gebruikt wordt. Voor een redelijk door-latende grond moet men ongeveer 10-15 meter per per-. soon rekenenper-.

Als men niet zoveel ruimte tot z~Jn beschikking heeft of als men een ondoorlatende soort grond heeft, kdn men een baktePie ptateau maken.

Het principe is dat het afvalwater afgeb~oken wordt door bakterien die in normale tuingrond voorkomen. Het plateau wordt gemaakt van cement of iets derge-lijks en heeft opstaande randen van 10 cm hoogte. Het plateau moet een oppervlakte hebben van 1 m2 per 'Ige-bruiker". Op het plateau komt eerst een laagje grind (5 cm) en daarop een laagje zand (ook 5 cm), Hier bo-venop komt tuingrond (+ 30 em).

Door het geheel in te graven (zie de tekening) Kan men toch zijn tuintje in stand houden en op de grone bloemen of groenten telen. Om een g ede spreiding van het water over het oppervlak te krijgen, zorgt men dat dit licht afloopt.

Voor aZZe verbindingen getdt: zorg dat ze Licht af-Lopen U Als :nen di t niet doet, kan een goede dccr'-stroming belem:nerd worden.

Als U huishoudelijk afvalwater in de septic tank of l'echtstreeks in een ZaKT)ut ~'lilt voeren, moet U voor-Komen dat dit water teveel vet of zeep bevat. Deze stoffen kunnen in de septic tank de bakteriewerking

(40)

3A.CTERIE fig. 4. PLATEAU tuingrond ·):1~WJ:-;:and pind deksel fig. 5. rooster

takken of stukken hout

ernstig storen en in de zakput vormen ze een vetach-tige laag op de wand, vraardoor deze geen water meer door kan laten. Als men geregeld vet- of zeepwater kwijt Hil, verdient het aanbeveling in de afvoer van de "gootsteen" naar de septic tank of eventueel zakput of drainagesysteem, een putje te bouwen dat men vult met takken of stukken hout (zie fig.S).

Dit hout zal het vet en de zeep vasthouden en het water via een roosterdoorlaten naar zijn bestem-mingo Van tijd tot tijd dient het hout vervangen te \·;0rden. Bet hout uit het putje moet U verbranden. Tot slot nog:

Voorkom dat U bakteriedodende stoffen als vergif, sterk loog of sterk zuur in de septic tank of aqua privy brengt.

Als de tank op de een of andere manier niet meer werkt, bijvoorbeeld omdat hij lange tijd buiten

ge-~ruik geweest, moet hij geleegd, schoongemaakt en opnieuw met water gevuld worden. Bij normaal ge-l::!'uik zal di t echter niet voorkomen.

(41)

l _______ ..---__ ...

~_

.. _. ___ . _____ _

.:::. '.( t:t R' \.0 C-,? N A.A.::? cn,'e ~·jd>!""<.f'l WAT ":':r ZA.NCVlLTG~ I J ;

I~!

) ! / " ' " i

L ___

+

__

J N .... ""'Z b"?~n.i,~A"'Q !>T~OI·U::rH.J 1''''AT"5"~ -40-I ' \, , ''-" , ? t \._ ,"

Vanni t de septictr:nk knl. :if: ~i:~-' voer op drie manin'u,

gc"c}:ic-den:

1 • .ooer over loop (;~) neWT C' (2)'.

verdeelr)ut (~,) 1,.1it~ de ~lf~/~"J',::",· ster nasr een uitge~trckL t~­

vloc ter:r,:-in tren-~: 1 crt.

voorzion van J~~ince~~~i~cn,

2.

Door zan biol

.aarnn eon over10cf n~~r 0~L

wutt?r voert.

Door tcrr€intcvl~ci~"G ~o~3t

vo(~l:t. ui,t de cVt:rl(!,~)p ~£t de

gron~ en de t~ite~lucht i~

V(·l'~,'~.:' ,,'lirl\~ l.: r; bI'(~Cl: t ;>~~::.tf~rti j

ba.ct eri (;:1 d08r ox:,"d; .. t:lc C:!l ....

Bcha0c j~ wcr~cn.

Aan lID:'.r d,:' plG.utsel:i.j!,;.c,' t00st~n; van ~e onlcrSronJ.

vcrdeclput (~) ~ocrcn

n nu&r een of ccer

3. Van ecn verJcelput voert c~n

overloofJ rln.C;.r t~~~n ~~~.r~:~\::ilt ~r~

Bij e~n dcrsclijk~ s&~cnstQl-1 ~JOl:d,t re1 ____ ~::~~~:· .. ~ bG:---~C~t.~ '-::ri

1:6 t de: .:, trcr.:i.n ~.~ 'V [~n he. t ?~'r ,~,,!::~,-._­

vIa tc 1"' ~ "\;.'j~ ~1 d= i c~: .I(,.i~1i •

,~inirnurn helling afvoert~izan:

2 C~ p~r n; grot~ra hallin; ic rla.:lulj.t; OL1cat i1et vocL't tc a ~

afvlc~j.t net achtcrlat van

het vuata yuil (aanko~ken).

Inwen(;'i.Ge diamot,:,:.~ 1",iiL:2:e,!:

bij voorkeur nia: kleinar

Referenties

GERELATEERDE DOCUMENTEN

This research programme aims to assess the effects of climate change and autonomous adaptive strategies (i.e. adaptation strategies undertaken by autonomous actors such as farmers

existing data – the FAIR research data, (open) government data and the datasets that are not so easy to find.. This blog post will give you some ideas and starting points, but by

The material initially comprises only the soft and ductile austenite phase which due to the phenomenon of mechanically induced martensitic transformation, transforms completely to

So far, po- sitive evidence of burnt chaff has been found in five pits: one Einzelgrube to the east of a house, two Längsgruben dug along the eastern walls of houses, one Einzelgrube

Hoeveel kilometer reist u ongeveer per dag op en neer naar werk?. Meer dan

So although the general attitude towards rural tourism is positive, policy makers still have to be cautious because people aren’t likely to participate in rural tourism and

The texture in diffusion-grown layers of disilicides MeSi2 (Me = Mo, W, Ti, V, Nb, Ta) and compounds with related structures (NbGe2, TaGe2, TiGe2, TiNiCu)es MSi2 (M = Mo, W, Ti, V,

The main objective of this report is to provide Blessed Generation with advice on how to involve poor people in managing a business when designing a suitable marketing channel for